Seal and centralizing means for floating tank covers



United States Patent Ofllice 3,@48,Z98 Patented Aug. 7, 1952 3,048,298 SEAL AND CENTRALIZING MEANS FOR FLOATING TANK COVERS John D. Lessing, Palos Verdes, Richard J. Atkinson, Glendale, and Ralph K. Cadwell, Los Angeles, Calif., assignors to Lacy Manufacturing Company, Los Angeles, Calif., a corporation of California Filed May 16, 1960, Ser. No. 29,504 4 Claims. (Cl. 220-26) Our invention relates to storage tanks and relates more particularly to storage tanks in which the roof or cover floats on the liquid stored therein.

In storage tanks of this type, the cover which floats on the liquid will raise or lower as the tank is filled or emptied. In order to provide for this movement there must be a space between the cover and the vertical side walls of the tank and it is desirable that this space be sealed in order to prevent loss because of evaporation, to exclude foreign matter, and to reduce fire hazard.

t is furthermore highly desirable that there be a centralizing means to hold the cover in a. centralized position spaced from the side walls of the tank to prevent any binding action which would interfere with the free floating movement of the cover.

It is an object of our invention to provide a centralizing means for holding the cover in a substantially centralized and free moving position which centralizing means includes a multiplicity of elements having torsion means which resist lateral movement of the cover.

It is a further object of our invention to provide in a storage tank having a floating roof or cover, centralizing means for the cover which has centralizing elements extending from rim of cover outward engaging friction shoes which slide vertically on inner wall of tank. Each of these centralizing elements or centralizing means has torsion spring means to which lever means is connected, the lever means being engageable by the cover means and being operable so that whenever the cover moves in a lateral direction, a torsion will be placed in certain of the torsion spring means to resist further lateral movement of the cover and tending to return the cover to a centralized position.

It is a further object of our invention to provide a centralizing means having an interconnecting element embodying torsion means, this interconnecting element being connected to the shoes which engage the side wall of the tank and to the cover at spaced positions so that the shoes will be properly supported against the side wall I of the tank in their intended operative positions.

It is a further and important object of our invention to provide a centralizing means of the character referred to which will be simple to install. The mounting brackets are all welded or otherwise secured in place. In fabrication it is only necessary to install the centralizing element in proper operating position on these mounting brackets.

It is a further object of our invention to provide a centralizing means in which there will be a longer life expectancy because of the elimination of small parts which are subject to corrosion.

It is also an object of our invention to provide centralizing means in which the number of parts are reduced, and the parts employed are of simple design for manufacture.

Other objects and advantages of the invention will be be made evident in the course of the following detailed description of one form of our invention.

Referring to the drawings:

FIG. 1 is a vertical sectional view showing the sealing and centralizing means of our invention;

FIG. 2 is a fragmentary plan view of FIG. 1;

FIG. 3 is an enlarged cross sectional view taken at the vertical edges of adjacent shoes and showing the manner in which a seal is provided between those edges;

FIG. 4 is an elevational view showing the connecting element of our invention which incorporates the torsion means; and

FIG. 5 is an end view of FIG. 4.

As shown in the drawings and particularly FIGS. 1 and 2, 11 is the side wall of a tank in which liquid is to be stored. The side wall 11 is usually cylindrical. Within the side wall of the tank is a cover 12 having a horizontal wall 14 and an upstanding rim 15. Where the side wall 11 is cylindrical, the upstanding rim 15 is also cylindrical and the difference in diameters of 11 and 15 provides an annular space 16. As shown'in FIG. 1, the cover 12 floats on the liquid indicated at 17 and as the tank is filled, the cover moves upward and as the tank is emptied the cover will move downward along with the liquid level.

Engageable with the inner wall or surface of the side wall 11 is a plurality of shoes 20 which, as shown in \the plan view, are separated by small spaces 21. These small spaces 21 may be suitably sealed by a flexible sealing member such as shown at 22 in FIG. 3. The shoes 20 are vertically slidable within the side wall 11 moving upward and downward with the cover 12.

For the purpose of forming a seal between the side wall 11 and cover 12 a suitable flexible sealing apron 24 is secured to the upstanding wall 15 as indicated at 25 and to the upper ends of the shoes 20 as indicated at 26.

The centralizing means of our invention comprises a series of connecting members or torsion elements or means illustrated in detail in FIGS. 4 and 5, which connecting members are secured between the shoes 20 and the cover 12 as will be described shortly. Referring to FIGS. 4 and 5, each connecting element consists of a pair of parallel arms 30 and 31' having trunnions 32 and 33 formed at one of the ends thereof. 7 The opposite ends of the arms 30 and 31 are connected to torsion means which consist of torsion bars 34 and 35 which are aligned with each other and which, as shown, extend substantially at right angles to the arms 30 and 3-1. Formed at the adjacent ends of the torsion bars 34 and 35 is a lever 36 consisting of two rod portions 37, the rod portions being connected at one end to the torsion bars 34 and 35 and being connected together at their opposite ends as indicated at 33. It will be noted that the lever 36 extends at an angle as indicated in FIG. 5 with respect to the plane in which the levers 30 and 31 rest.

This connecting element is incorporated in the combination as followsa pair of fixtures 40 having horizontally extending and aligned openings 41 secured to each shoe 20 in horizontal spaced relationship as shown best in FIG.

2. Thetrunnions 32 and 33 extend through the openings 41 of this pair of fixtures 4t). Mounted on the upstanding rim 30 are four supporting brackets 43, each of which has horizontal slot 44. These brackets 43 are positioned so that the torsion element is supported adjacent the outer ends of the torsion bar portions 34 and 35 and is also supported near the adjacent ends thereof. In addition, there is a retaining lug 46 on the rim 15 which extends outwardly between the rods 37 of the lever 36. This retaining lug provides a vertical slot 47 which is open at its upper end. The lever end rests in this slot and prevents the shoe from falling outward should the tank be filled to overflowing condition with the upper part of the shoe projecting upward from the tank.

It will be noted that the centralizing elements or torsion elements are so proportioned and designed that when they are installed in place that they will, when in a position of 3 rest, tend to hold the cover 12 in a substantially centralized position and to hold the shoes 20 against the inner surface of the side wall 11 of the tank. The amount of pressural engagement is determined by the angularity between the arms 30 and 31 and the lever 36.

When the parts are in their normal position and by normal position we refer to one in which the cover 12 is centralized, the lever portion may be swung slightly toward the arms 30 and 31 slightly decreasing the angularity between the two shown in FIG. with the result that there is a slight torsion or twisting in the torsion members or portions 34 and 35. There is at this time a slight pressure outwardly against the shoes and inwardly against the cover 12.

Should the cover 12 move sidewardly from the position shown in FIG. 1, it will cause a deformation of the shape of the centralizing elements at the side toward which the cover is moving with the result that the angularity between the arms and 31 and the lever 36 is decreased and this causes a greater torsion to be imposed in the torsion bars 34 and 35. The pressure against the shoes increases but more important the pressure against the upstanding rim 15 increases and this force exerted thereagainst resists further sideward movement of the cover and also tends to return the cover to its normal centralized position.

It will be noted that the centralizing elements are each in one piece and of simple dependable construction. They are simple to install by squeezing the ends of the arms 30 and 31 together so that the trunnions 32 and 33 may extend through the openings 41 and the brackets 40. The torsion bars are hooked into retaining lug 46 horizontally into the slots 44.

A further important feature of the invention is that the centralizing member has a balancing supporting action because it engages the shoe at two places and engages the upstanding rim 15 at five diiferent places.

The outstanding feature of our invention is that the centralizing elements may be so shaped and proportioned to readily maintain the cover 12 in a centralized position. The feature of having the torsion bars 34 and 35 eliminates all sliding parts and also eliminates any parts which elongate and retract.

Although FIGS. 4 and 5 illustrate the preferred form of our invention, it would be possible to use centralizing means including only the arm 30, the trunnions 32, the torsion bar 34 and one of the rod portions of the arm 36. In this form of our invention, however, the balancing feature of the double arms and trunnions and the balanced supporting of the shoes 20 would not be present.

From the foregoing description the various features and advantages of our invention are apparent. It is recognized that modifications may be made without departing from the spirit and scope of the invention and it is intended that the scope of the invention be construed in accordance with the appended claims.

We claim:

1. In combination in a storage tank having a vertical side wall, and a floating cover adapted to float on the liquid in said tank: a plurality of contact shoes in slidable engagement with said side Wall of said tank; sealing means between said shoes and said cover; centralizing means for said cover operable between said shoes and said cover, said centralizing means including a pair of spaced arms each having one end rotatably connected to one of said shoes; a torsion member having one end thereof connected to the other end of one of said arms and a second torsion member having one end thereof connected to the other end of the other of said arms,

said torsion members extending toward each other, each of said torsion members being rotatably connected to said cover; and a U-shaped lever having the end of each leg thereof connected to a respective other end of said torsion members, said lever being engaged with said cover whereby lateral movement of said cover towards said side wall will carry said lever to place a torsion in said torsion members.

2. In combination in a storage tank having a vertical side wall, and a floating cover adapted to float on the liquid in said tank: a plurality of contact shoes in slidable engagement with said side wall of said tank; sealing means between said shoes and said cover; centralizing means for said cover operable between said shoes and said cover, said centralizing means including a pair of spaced arms each having one end connected to one of said shoes; a torsion member having one end thereof connected to the other end of one of said arms and a second torsion member having one end thereof connected to the other end of the other of said arms, said torsion members extending toward each other, each of said torsion members being rotatably connected to said cover; and a U- shaped lever having the end of each leg thereof connected to a respective other end of said torsion members, said lever being pivotally engaged with said cover whereby lateral movement of said cover towards said side wall will carry said lever to place a torsion in said torsion members.

3. In combination in a storage tank having a vertical side wall, and a floating cover adapted to float on the liquid in said tank: a plurality of contact shoes in slidable engagement with said side wall of said tank; sealing means between said shoes and said cover; centralizing means for said cover operable between said shoes and said cover, said centralizing means including a pair of spaced arms each having one end rotatably connected to one of said shoes, a rod-shaped torsion member having one end thereof connected to the other end of one of said arms and a second rod-shaped torsion member havin one end thereof connected to the other end of the other of said arms, said torsion members extending toward each other, each of said torsion members being rotatably connected to said cover; and a U-shaped lever having the end of each leg thereof connected to a respective other end of said torsion members, said lever being engaged with said cover whereby lateral movement of said cover towards said side wall will carry said lever to place a torsion in said torsion members.

4. In combination in a storage tank having a vertical side wall, and a floating cover adapted to float on the liquid in said tank: a plurality of contact shoes in slidable engagement with said side wall of said tank; sealing means between said shoes and said cover; centralizing means for said cover operable between said shoes and said cover, said centralizing means including a pair of spaced arms each having one end connected to one of said shoes; a torsion member having one end thereof connected to the other end of one of said arms and a second torsion member having one end thereof connected to the other end of the other of said arms, each of said torsion members being rotatably connected to said cover; and a lever having corresponding parts thereof connected to respective other ends of said torsion members, said lever being engaged with said cover whereby lateral movement of said cover toward said side wall will carry said lever to place a torsion in said torsion members.

References Cited in the file of this patent UNITED STATES PATENTS 199,810 Evans et al. Jan. 29, 1878 1,178,605 Thompson Apr. 11, 1916 1,930,953 Hampton Oct. 17, 1933 2,651,433 Mjellem Sept. 8, 1953 2,696,930 Moyer Dec. 14, 1 954 2,855,122 Ulm et al. Oct. 7, 1953 

